This invention relates to motion picture sound film, and more particularly to novel apparatus by which to splice motion picture sound film to achieve precise correspondence between the sound and the picture frames.
In motion picture sound film the continuous sequence of longitudinally separated picture frames is disposed intermediate the lateral sides of the film. A multiplicity of longitudinally spaced drive sprocket openings are formed in the film between the picture frames and one lateral side of the film, and a magnetic sound stripe is provided between the picture frames and the opposite lateral side of the film.
However, in motion picture sound cameras and corresponding sound projectors the magnetic sound pickup head is spaced longitudinally from the picture frame diaphragm opening. Accordingly, the sound recordings on the magnetic stripe are displaced longitudinally from the picture frames to which they relate.
In conventional editing and splicing, the film is cut transversely completely through on a single transverse line. Therefore, the picture frame and sound recording immediately adjacent the transverse cut are not related, and this lack of correspondence between sound and picture is disturbingly noticeable, particularly when the visible action includes speaking, since movement of the lips do not correspond with the sound playback.
The only known procedure attempted heretofore to provide exact correspondence between sound and picture frames of motion picture sound film, involves the steps, following conventional splicing described hereinbefore, of utilizing the end portion of the sound track from the edited portion of film to replace, by re-recording, that other end portion of the sound track on the spliced film that does not relate to any of the picture frames in the spliced film. This re-recording of sound involves very complex and costly equipment, and hence is impracticable for use by anyone other than large studios.